Note: While thinking about your options, please consider the placements of the Jump Pads in some of the maps. Some maps have platforms that can be accessed by using a Jump Pad from underneath them, and I imagine that if they were to try incorporating these platforms into BBO, it wouldn't work. The Marecraft was originally going to be in BBU but was scrapped for unknown reasons, but I believe it's precisely because of the towers that require the Jump Pads directly below to reach them.

No Bear's Land and Haunted Castle in particular are pretty much destined to be included in BBO. They're both perfectly sized and designed to work around BBO's larger scale and mechanics, and their multiple pathways help emphasize the teamwork aspect of the game.

The Spaceship is an absolute classic, and honestly, as much as I feel that some maps would work better as the third choice due to their design, I picked this map because BBO could use an extra map that caters specifically towards close encounters. Let's not kid ourselves, if this map was in the game, I would honestly think more BBG players would swing by this game every once in a while just to practice the different gameplay in a familiar setting to make themselves more comfortable, not to mention the fact that 1v1s would happen way more often.

Aztec(it's similar sorta way to Neo and most of BBO maps are open so is this) also if they ever decide to re introduce capture flag to bbo this would work well with it
Ausement park.
Haunted Castle (again open map works sorta like Neo with high sides and a pit in the middle) although maybe get rid of the underground bit.

Maps with lots of jump pads should be avoided like the plague because they are disgustingly unbalanced in Overclock. As much as I love Desert Airmine, i cannot even begin to imagine dealing with ice traps on that map. Additionally, Overclock tends to favor large maps with a mix of close and long range combat. This is because characters are faster and cover distance more quickly , and need room to run and hide so they can regenerate their health. Additionally, unlike BBG in Overclock you cannot switch to another character, so if you get stuck with a situational weapon it can be an issue. To solve this problem. Maps with a variety of combat situations allow characters and weapons to be played to their strengths far more consistently.

Haunted Castle fits most of this perfectly, although it does unfortunately have some importantly placed jump pads. Abusement park is also great for this, except it has more of an emphasis on close combat. This is better than vice versa, however, as most long range weapons are still usable in close range in Overclock (which isn't true the other way around). I also tend to think that Abusement Park has a great map layout that is fun to play on, balanced, and promotes strategic play.

Battlefield Airpad is another good choice, because it has less jumpads and is also quite large. Shotguns would perform poorly here, however, all other weapons could be used fairly effectively. Shotgun users would need to stay on the outskirts of the map to be competitive, but they also wouldn't be dead weight. Battlefield Airpad is also very well designed for Overclock 1v1's as well, and i could see it rivaling sporest for sniping matches.

Several other maps are also good candidates, such as Gold Digger, Huggable Factory, and Facing Temples. But the other maps have issues in my opinion, either having too many jump pads, unbalanced gameplay for Overclock, or designs that don't fit well with Overclock's mechanics. Spaceship could be an exception, and it would definitley be a good choice for certain types of 1v1's. It would need to be scaled up slightly, but the close quarters and fast pace could be a nice change for Overclocks map selection.

Unmentioned maps are probably too terrible of an option for me to consider writing about. However, there are a couple such as MareCraft Carrier that could actually be pretty solid if implemented well.